Nadal, who is 31 on Saturday, won his first Roland Garros crown in 2005, the first of four successive victories before claiming a further five in a row between 2010 and 2014.

The Spaniard is only one of two players – the other being German Alexander Zverev – to win multiple clay-court titles this season. He won his 10th titles at Monte Carlo and Barcelona as well as his 30th Masters title in Madrid.

“It is the biggest challenge in the game to beat Nadal over five sets on clay in Paris,” Henman told BBC Sport.

The only other player to win 10 or more titles at a single Grand Slam is Margaret Court, who won 11 Australian Opens between 1960 and 1973.

“It would be one of the biggest achievements in tennis and one of the biggest in any sport,” added Henman.

“To have been so dominant at one of the biggest events in our sport is just incredible.”

Nadal has only lost two matches at the French Open, to Robin Soderling in 2009 and Novak Djokovic in 2015

A defeat by Dominic Thiem at the Rome Masters is Nadal’s only loss on clay this season

No concerns over Murray’s form

After a season hampered by injuries and illness, world number one Andy Murray beat Russian Andrey Kuznetsov in the first round on Tuesday and Henman believes the Scot will be looking to “build round by round”.

“I wouldn’t say Murray is favourite but he is the number one in the world for a reason,” Henman said.

“I haven’t been concerned by his form because he has been ill and injured.

“If he can stay healthy and injury free, he will start winning matches and tournaments because he is one of the best players out there.”

The Scot won his opener in four sets to set up a second-round match with Slovak Martin Klizan. He now faces a potential third-round clash with Argentina’s Juan Martin del Potro.

“Klizan is an awkward player but I expect Andy to come through that and Del Potro in the third round is a much bigger challenge.

“Irrespective of what happens in Paris, on the grass, with his record at Queen’s and Wimbledon, he will definitely be one of the favourites for those titles.”

Agassi can help Djokovic

Former world number four Henman believes Andre Agassi will have “lots to offer” Novak Djokovic, after the American took over as the Serb’s coach for the first week in Paris.